Alterations of blood pulsations parameters in carotid basin due to body position change

Abstract

The velocity of the pulse wave (PWV) propagating through the vascular tree is an essential parameter for diagnostic the state of the cardiovascular system especially when it is measured in the pool of carotid arteries. In this research, we showed for the first time that the time of the blood-pressure-wave propagation from the heart to the face is a function of the body position. Significant asymmetry and asynchronicity of blood pulsations in the facial area were found in a recumbent position. Parameters of blood pulsations were measured by an advanced camera-based photoplethysmography system in 73 apparently healthy subjects. Most likely, observed changes of the blood-pulsation parameters are caused by variations of the arterial blood pressure due to hydrostatic pressure changes, and secondary reaction of blood vessels in response to these variations. Demonstrated feasibility of PWV measurements in the pool of carotid arteries provides considerable advantages over other technologies. Moreover, possibilities of the method to estimate physiological regulation of the peripheral blood flow (particularly, as a response to the gravitational changes) have been demonstrated. The proposed concept allows development of non-invasive medical equipment capable of solving a wide range of scientific and practical problems related to vascular physiology.

Contactless Assessment of Cerebral Autoregulation by Photoplethysmographic Imaging at Green Illumination

“…This illumination was chosen because several research groups working with the reflection-mode PPG reported that the largest intensity modulation at the heartbeat frequency was observed at the green light modulation (Verkruysse et al, 2008; Kamshilin et al, 2011; Fallow et al, 2013). PPG-system design was described in details in our recent paper (Kamshilin et al, 2018). Briefly, it consists of a digital monochrome CMOS camera (10-bit model GigE uEye UI-5220SE of the Imaging Development Systems GmbH) integrated with an illuminator with a polarization filter.…”

“…To evaluate CBF dynamics we used an amplitude of the pulsatile component (APC) of the photoplethysmographic waveform that shows modulation of the light reemitted from the brain at the heartbeat frequency (Allen, 2007). Spatial distribution of APC over the cortex was calculated using an algorithm described in details in our recent paper (Kamshilin et al, 2018). Briefly, the algorithm includes the following steps.…”

Contactless Monitoring of Microcirculation Reaction on Local Temperature Changes

“…Recorded video, ECG and temperature data were processed by using custom software implemented in the MATLAB ® platform. The algorithm of PPG signal processing was described in detail in our previous papers [14,19]. Briefly, we calculated the spatial distribution of the blood pulsation amplitude (BPA) over the facial area.…”

“…Temperature data were recorded every 2 s synchronously with the recording of video frames. A detailed description of the experimental setup is given in our recent paper [14]. Video frames, ECG and temperature data were downloaded to the computer's hard drive for subsequent offline processing.…”

“…The black curve in Figure 2A shows our simultaneously-recorded ECG signal. R-peaks of the ECG signal were used to evaluate the mean shape of the pulse over 30 cardiac cycles, as illustrated in Figure 2B [14].…”